1. Field of the Invention
The present invention relates to a method for obtaining vector data for a line having coordinate values input from a pointing device and a thickness and/or density in accordance with pen pressure values, a computer program for executing the method, and an associated image processing apparatus.
2. Description of Related Art
Known image processing apparatuses and image processing software have displayed a line having a thickness and/or density responsive to pen pressure when a user inputs a line via a pointing device, such as the combination of a pen and tablet or digitizer.
With this type of image processing apparatuses in the past (whether they were dedicated image processing apparatuses or general-purpose computers running image processing software), because the data sent from the pointing device is coordinate value data and pen pressure data for each pixel, a large amount of data is involved. For this reason, some method is used to compress the data used for plotting and image-processing the input data. The method generally used of reducing the amount of data is that of determining the arithmetic mean of a prescribed number of continuous data.
When applying this arithmetic mean processing, a part of a line that exhibits a sudden curve is smoothed out too much by taking the arithmetic mean, imparting rounding thereto, thereby presenting the problem of not being able to plot the line as input by an operator. In the same manner, a sudden change in pen pressure is also smoothed by the arithmetic mean, so that the change in pen pressure cannot faithfully reproduced.
Although high-resolution apparatuses (with a large number of display pixels) are available for the purpose of faithfully following an input curve and the pen pressure from a pointing device, if the input data is stored as is in this case a large amount of memory capacity is required to store the input data. An additional problem is that of a large amount of time being required to process the large amount of data used for creating and editing illustrations and the like.
Hand-drawn strokes are subject to effects of a shaky hand or unsteady hand, so that they are not smooth, and considerable experience is required in order to eliminate shakiness, making it quite difficult to achieve the curve intended by the user. There is known software for smoothing hand-drawn strokes, but such smoothing processing does not start, or the results of the processing could not be displayed until a stroke (path) of a hand-held pen comes to an end, thereby presenting the problem for the user of a delay in the verification of the results.